Contributions to the Data on Theoretical Metallurgy: [Part] 7. The Thermodynamic Properties of Sulphur and its Inorganic Compounds Page: 16
ii, 154 p. : tables ; 24 cm.View a full description of this report.
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DATA ON THEORETICAL METALLURGY.-VII
energies of sublimation of these crystalline varieties have been approxi-
mated from vapor-pressure data (68).
s AH298.1= 12,250
SO3(a) = SO(g)
AFo208.1= 573
SAH298.1= 13,080
S03(0) = S03(g)
AF298s.= 700
SOa(7)=SO3(g9) AH298.1= 16,500
8AF298.1= 1,330
From these figures and those for the reaction 2S(rh)+302=2SO3(g),
the following results are obtained:
2S(rh) +30 = 2S0() H298.1= -210,170
AFs98s.i= --176,440
(AH298.1= -211,830
AF298.1= -176,690
2AH298.1= -218,670
)AF298.1= -177,950
S04--(aq.); HSO4-(aq.).-Smith and Mayer (152) have obtained
AF298.1=--176,540 as the free energy of formation of SO4--(aq.).
As the free energy of formation of H+(aq.) is zero, this figure is also
the free energy of formation of H2SO4(aq.). This value is in good
agreement with the result, AF298.1= -176,500, adopted by Lewis
and Randall (88). Its order of magnitude may be checked by inde-
pendent means. Roth (137) has obtained AH298.1= -194,100 for the
heat of formation of H2SO4(l). (In assigning this value to 298.10 a
small temperature correction is neglected.) By the extrapolation of
available data, Latimer, Hicks, and Schutz (87) have arrived at
AH29s.1= -20,900 for the heat of dilution of H2SO4(l) to infinite dilu-
tion. Therefore, AH298.1= -217,000 for the reaction S(rh)+H2I
-202=2H+(aq.)+SO4--(aq.). The entropy of this reaction is ob-
tained as AS298.1= -134.2 from values already recorded (70). Hence,
the free energy of this reaction is AF298.1= -175,000. The measure-
ment of Smith and Mayer should be given preference over this result.
Hamer (38) has studied the reaction HSO4-(aq.)=H+(aq.)+
SO4--(aq.) and obtained K298.1=0.0121, which corresponds to
AF298.1=2,615. From this and the free energy of SOc-(aq.),
AF298.1=--179,160 is obtained for the formation of HSO4-(aq.)
from the elements.
SULPHUR MONOXIDE
Specific heat.-The specific heat of SO (g) may be computed with
sufficient accuracy by adding the vibrational specific heat to the
classical value of the translational and rotational specific heat,
C, ,r+,o,=6.95. The vibration frequency is w=1,117.6 cm-1 (104),
hv
corresponding to 0=- -= 1,601. The total specific heat may be written.
SO(g): C,=6.95+ C,b= 6.95+E( 1,601) (63)
where E() is the Einstein specific-heat function for one degree of16
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Kelley, K. K. Contributions to the Data on Theoretical Metallurgy: [Part] 7. The Thermodynamic Properties of Sulphur and its Inorganic Compounds, report, 1937; Washington D.C.. (https://digital.library.unt.edu/ark:/67531/metadc66396/m1/18/: accessed April 20, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.